Just as world leaders gather for this year’s COP30 climate summit in Brazil, the government’s announcement of its intention to significantly change New Zealand’s climate change law upends years of cross-party consensus.

All of the proposals pose serious problems, but the change to the zero-carbon provisions in the Climate Change Response Act 2002 runs counter to the underlying purpose of the act to provide accountability for climate change policy.

The government proposes to simplify emissions reduction plans, which are produced every five years to set out policies and strategies to decarbonise every sector of the economy.

It also wants to remove the Climate Change Commission’s role in providing independent advice on emissions reduction plans, and allow more frequent revisions of these plans without public consultation. The changes would also adjust timelines for emissions budgets and reports, and relax deadlines for the government’s response.

In earlier research, we explored why climate change is an especially difficult policy issue. One of the chief reasons is that it is a long-term problem that needs action now.

Political systems are not good at addressing long-term problems. As public policy expert Jonathan Boston has demonstrated, democracies suffer from a short-term focus and find it hard to ask voters for commitments to fix a problem that will unfold over decades.

Consequently, countries have often announced targets for emissions reductions for dates that are decades away, and then walked off.

The classic New Zealand example is when Tim Groser, who was minister for climate change between 2010 and 2015, consulted the public about what New Zealand’s Paris Agreement target should be, but declared that domestic policies to achieve the target were a separate matter for some other time.

There is a tendency for governments to make grand statements on targets without awkward detail about what we have to do to reach them – or to do as little as possible so as not to upset voters.

But we know that won’t work. New Zealand went through a long period of that kind of climate policy making, and it shouldn’t go back.

Why we have climate law and a commission

The solution we settled on for emission targets and policy in 2019 was the Climate Change Response (Zero Carbon) Amendment Act. The act’s core elements are targets, budgets, plans and independent advice.

The long-term emissions targets for 2050 (net zero for long-lived greenhouse gases and a recently weakened target for shorter-lived methane) are supported by five-yearly emissions budgets, which show what has to be done in each period to stay on track for the target.

These budgets break down the distant target into a series of closer, smaller and more manageable ones. Then, for each budget period, there is a plan that sets out the policy actions in different sectors that, taken together, should produce a viable path to the necessary emissions reductions.

The Climate Change Commission is part of this policy system to provide transparency and independent judgement.

It formulates advice on targets, budgets and plans (and on a number of other matters), and that advice is made public. The government may or may not foll